Monteggia-like lesions – treatment strategies and one-year results

Introduction: The eponym “Monteggia fracture” includes various patterns of complex fracture-dislocations of the proximal ulna and radius, which are not well defined yet. They are frequently described as Monteggia-like lesions or Monteggia equivalent injuries. Until today, these injury patterns have been reported rarely. The objective of this retrospective study was to better define patterns of injury and to document the short-term results of treatment with current fixation techniques. Methods: Ten patients with a Monteggia-like lesion were included in this study and clinical and radiological follow-up examinations at an average of 12.3 months after the trauma were performed. For clinical follow-up the Mayo Modified Wrist Score, the Mayo Elbow Performance Score, the functional rating index of Broberg and Morrey, and the DASH score were utilized. Results: Osteosynthesis of the ulna was performed using a proximally contoured or precontoured LCP (locking compression plate) in all patients. All patients had a fracture of the radial head. All patients with a Mason type III radial head fracture received a cemented bipolar radial head prosthesis. All Mason type II fractures were treated with open reduction and internal fixation using mini screws. In all Mason type I fractures the treatment of the radial head dislocation was by closed reduction. Associated coronoid fractures were stabilized with lag screws through the ulnar plate or with independent lag screws after reduction of the fracture. According to the aforementioned scoring systems good to excellent results could be achieved. Conclusions: Our findings demonstrate that good or excellent short-term results can be obtained if the injury is classified correctly and a standardized surgical treatment of all components of the injury is achieved. Further studies with larger patient populations and longer follow up periods are needed to evaluate long-term effectiveness of this treatment concept.

head prosthesis. All Mason type II fractures were treated with open reduction and internal fixation using mini screws. In all Mason type I fractures the treatment of the radial head dislocation was by closed reduction. Associated coronoid fractures were stabilized with lag screws through the ulnar plate or with independent lag screws after reduction of the fracture. According to the aforementioned scoring systems good to excellent results could be achieved. Conclusions: Our findings demonstrate that good or excellent short-term results can be obtained if the injury is classified correctly and a standardized surgical treatment of all components of the injury is achieved. Further studies with larger patient populations and longer follow up periods are needed to evaluate long-term effectiveness of this treatment concept.

Introduction
Monteggia fractures are rare injuries of the forearm and were first described by Giovanni Battista Monteggia in 1814 as a fracture of the shaft of the ulna combined with an anterior dislocation of the radial head [1]. Monteggia injuries account for only 2-5% of all proximal forearm fractures [2]. In 1967, Bado introduced the concept of a Monteggia lesion and presented a classification into four types depending on the direction of the radial head's dislocation and the angulation of the fracture of the ulna [3], [4]. Type I describes a dislocation of the radial head in anterior, type II in posterior, and type III in lateral direction. Type IV is defined as a fracture of both bones of the forearm with dislocation of the radial head [4]. Furthermore, Bado described Monteggia equivalent injuries which differed in radiological appearance but possessed similar characteristics especially in the mechanism of injury and in its treatment. Type II injuries are most common (about 80%), followed by type I (about 15%), while type III and IV injuries are rare (all together 5%) [2]. Jupiter further classified the posterior Monteggia lesion (Bado type II) depending on the location and type of the ulnar fracture as well as the pattern of radial head injury [5], [6]. In type IIA, the fracture of the ulna involves the distal part of the olecranon and the coronoid process; in type IIB, the fracture involves the transition from metaphysis to diaphysis, distally to the coronoid process; in type IIC, a diaphyseal fracture is present and in type IID, the fracture extends from the olecranon to the proximal half of the ulna. Radial head fractures were classified in 4 types: type 0: no fracture; type 1: one part fracture; type 2: two part fracture; type 3: three part fracture; type C: comminuted fracture [4], [6]. The Bado and Jupiter classifications have been applied more frequently in the literature due to considerations of surgical practicality [3]. However, over the years additional injuries, such as radial head fractures, coronoid fractures, and combined radial head and coronoid fractures have added complexity to the classification of Monteggia-related injuries [3]. Not all of those injuries are included in the Bado and Jupiter classifications. Therefore the eponym of Monteggia fracture includes various patterns of complex fracture-dislocations of the proximal ulna and radius which are not well defined yet [6]. Other authors describe Monteggia lesions which include additional injuries such as radial head fractures (Mason, grade I-III) and coronoid fractures (Regan and Morrey I-III) as Monteggia-like lesions or Monteggia-equivalent injuries [2], [6], [7]. Nevertheless, according to Giannicola et al., in Monteggia-like pattern, six essential lesions can be identified and each of them must be recognized and treated: 1. Ulnar fracture, 2. Radio-humeral dislocation, 3. Ulnohumeral dislocation, 4. Proximal radio-ulnar dislocation, 5. Radial fracture and 6. Distal radio-ulnar joint\interosseus membrane lesion.
The various combination of these critical lesions can explain the complexity and variety of their treatment [6]. However, despite these confusing classifications and descriptions: Monteggia lesions with concomitant injuries to the radial head and/or the coronoid process do exist. Therefore, they should be considered separately. We were able to diagnose and treat a total of 10 adult patients with Monteggia-like lesions which could be evaluated clinically and radiologically one year after the injury on average. The objective of this retrospective study was to better define circumstances and patterns of injury and to document the short-term results of treatment with current fixation techniques.

Materials and methods
Ten adult patients were surgically treated for a Monteggialike lesion between 2012 and 2014. Preoperatively, all patients received a CT-Scan of the injured elbow joint in order to rule out associated injuries and improve preoperative classification and planning. We defined a Monteggia-like lesion as a fracture of the proximal ulna distal to the end of the olecranon process with an associated dislocation of the radiocapitellar joint in combination with a radial head fracture alone or combined with a fracture of the coronoid process. All 10 patients met these criteria and their injuries were classified according to the systems of Bado and Jupiter et al. [4], [5]. Radial head fractures were classified according to Mason [8], fractures of the coronoid process according to Regan and Morrey [9], respectively. Demographics, injury patterns, and details of the surgical treatment were extracted from chart review. All 10 patients were available for follow-up examinations at an average of 12.3 months (range: 11-13 months) after the trauma. All patients were evaluated by the same experienced examiner blinded to the classification of injury. The average age was 52.4 years (range, 18-83 years). Six women and four men were included. In four patients the injury resulted from a motor-vehicle accident, in three from a casual fall from a standing height. The remaining three fractures were caused by a fall from a height of at least four meters. In four of the patients, the injury was part of a polytrauma including additional skeletal lesions in three, thoracic or abdominal trauma in two, and head injuries in two patients. The dominant arm was affected in eight patients. According to the classification of Bado two type I and eight type II fractures were seen. Two open fractures were classified grade I according to the classification of Gustilo and Anderson [10]. No patient had associated neurologic involvement. All eight Monteggia fractures with posterior dislocation of the radial head were further classified according to Jupiter et al. into two type IIa, four type IIb, two type IIc and two type IId fractures.
Osteosynthesis of the ulna was performed using a proximally contoured 3.5 mm LCP (locking compression plate) or precontoured 3.5 mm LCP Olecranon Plate (both Synthes GmbH, Umkirch, Germany) applied to the posterior surface of the ulna in dynamic compression mode ( Figure 1, Figure 2, Figure 3). All patients had a fracture of the radial head. A total of five were comminuted (Mason type III), three were classified as Mason type II and two as Mason type I. All patients with a type III radial head fracture received a cemented bipolar radial head prosthesis (CRFII, Tornier, Montbonnot, France). All type II radial head fractures were treated with open reduction and internal fixation using mini screws. Type I fractures were treated with closed reduction of the radial head dislocation under fluoroscopic control. According to the Regan and Morrey classification five type I, three type II, and two type III coronoid fractures were included. All type II and type III coronoid fractures were associated with a Bado type II fracture and stabilized using lag screws inserted through the ulnar plate or with independent lag screws after indirect reduction of the fracture. All patients were immobilized in a long-arm cast for one week. However, immobilization was discontinued for daily immediate passive motion and continuous passive motion  (CPM) without any restriction of movement starting at day 2 after surgery. Full weight bearing was allowed 6 weeks postoperatively. In order to prevent heterotopic ossifications non-steroid anti-inflammatories (Indomethacin 25 mg orally 3 times daily) were administered for 3 weeks. At the clinical follow-up examination the Mayo Modified Wrist Score (MMWS) [11] was used to assess the wrist function, while the Mayo Elbow Performance Score (MEPS) and the functional rating index of Broberg and Morrey [12] were used to assess the functioning of the elbow joint. The pain, satisfaction and stress resistance of the arm were recorded using the DASH Score as a subjective parameter [13]. The ROM of wrists, forearms and elbow joints was measured using a standard fullcircle goniometer bilateral. The elbow was tested for valgus and varus instability in maximum extension and in 30°of flexion. In order to evaluate posterolateral rotatory instability, the pivot-shift test [14] was performed in each patient and stability was graded as normal, mild, moderate or severely unstable. Grip strength was measured with a Jamar dynamometer (Fabrication Enterprises Inc., White Plains, New York) with the other hand serving as a control. After three consecutive bilateral measurements, the grip strength at the injured side was expressed as a percentage of the control, using a correction factor of 1.07 for the dominant hand over the non-dominant [15], [16]. Patient satisfaction was determined by a subjective satisfaction questionnaire according to Jungbluth et al. [15]. Pain at rest and during activity was measured with a visual analogue scale (VAS). Anteroposterior and lateral X-rays of the affected elbow joint were performed in all patients at the follow-up examination. Radiographs of the elbow were reviewed for capitellar osteopenia, degenerative changes, and heterotopic ossifications by an experienced and blinded radiologist. Capitellar osteopenia was graded as none, mild, moderate or severe according to Lamas et al. [17]. The degree of degenerative changes was classified according to Broberg and Morrey, as grade 0 (normal joint), grade 1 (slight joint space narrowing and minimum osteophyte formation), grade 2 (moderate joint space narrowing and moderate osteophyte formation), or grade 3 (severe degenerative changes with gross destruction of the joint) [12], [17]. Heterotopic ossification were graded as I, II, III or IV according to Brooker et al. [18]. In radial head prosthesis radiographic signs of loosening were assessed. Moreover, fracture union was defined as bridging bone on anteroposterior and lateral radiographs.

Results
Clinical follow-up examinations were performed at an average of 12.3 months (range [11][12][13]  According to the questionnaire for subjective patient satisfaction eight of the ten patients were satisfied with the results of the treatment and would choose the treatment regimen again. Eight patients reported no relevant restrictions of movement. All patients were able to return to their previous workplace and reached the same level of athletic activities as before the accident. The average VAS value was 1.0 (0 to 1) at rest and 1.7 (0 to 3) during activities.
Eight patients exhibited neither signs of capitellar osteopenia nor degenerative changes or heterotopic ossifications in the region of the elbow on conventional radiographs. Two patients with a radial head prosthesis showed mild osteopenia and grade 1 degenerative changes. These patients exhibited grade 1 heterotopic ossifications. No patient required revision surgery. None of the patients showed signs of loosening of the radial head prosthesis. Fracture union was achieved in all patients.

Discussion
Monteggia-like lesions are rare injuries and recommendations of treatment strategies are sparse. These injuries still represent a challenge to orthopedic surgeons. This challenge is further complicated since most studies about Monteggia injuries do not define Monteggia-like lesions as separate clinical entities [19]. Moreover, many studies on Monteggia injuries were carried out before the wide application of locking plates and some reports even have presented results of Monteggia injuries in children and adults together [4], [20], [21], [22]. Despite a better understanding of the biomechanical principles and advances in surgical treatment options, Monteggia injuries are still frequently associated with complications, poor functional outcomes, and high rates of revision surgery [23]. Furthermore, Monteggia injuries with associated radial head or neck fractures tend to have even worse outcomes [5], [19], [21], [24]. Givon [25]. Six of those had an accompanied posterior ulnohumeral dislocation at the time of injury. The 17 patients without ulnohumeral dislocation were assessed at a mean follow-up of 29 months. In these patients the mean elbow flexion was 127°and the loss of extension was 5°at follow-up. The mean pronation was 60°and supination 67°. The mean standardized DASH score was 23 and the mean Broberg-Morrey functional index score was 83. This accounted for six excellent, four good, six fair and one poor outcomes. Radiographic assessment of post-traumatic arthritis showed six patients with Broberg-Morrey grade 0, nine with grade 1 and two with grade 2 changes. Mild heterotopic ossification was present anteriorly in two patients.
Konrad et al. evaluated 27 Bado type II fractures as part of a population of 47 Monteggia injuries after a mean time of 8 years. In this series eleven patients suffered a radial head fracture, a fracture of a coronoid process, or a combination of both (Monteggia-like lesions) [23]. An intra-articular fracture of the radial head and a fracture of the coronoid process were correlated with a poor Broberg [21], [23], [24], [25]. According to Ring et al. the key treatment principle in Monteggia fractures is stable anatomic alignment of the ulna [24], [26]. In adults, this alignment is achieved with plate and screw fixation [24]. In contrast to all aforementioned studies all of our patients received osteosynthesis of the ulna using modern fixation techniques. In all cases a proximally contoured 3.5 mm LCP (locking compression plate) or precontoured 3.5 mm LCP Olecranon Plate was applied to the dorsal surface of the proximal ulna in dynamic compression mode. Since posterior tensile forces are encountered at the apex of the proximal end of the ulna with active motion, a plate applied to the lateral or medial surface of the ulna is mechanically inferior to a plate applied to the posterior surface of the ulna, which works as a tension band [24]. Ring et al. recommend fixation of the ulnar fracture with a stout plate, such as a 3.5-millimeter limited-contact dynamic compression plate, applied to the posterior surface of the ulna and contoured proximally to reach the tip of the olecranon [24]. Semitubular or onethird tubular plates as well as tension band-wire constructs seem to be not rigid or strong enough. The proximal contour allows to address the proximal fragment with more screws. The most proximal screws are oriented at 90 degrees to the more distal screws, creating a more stable construct [24], [26]. Until today, the question whether it is better to treat a severely comminuted fracture of the radial head associated with a Monteggia-like lesion with radial head ex-cision, reconstruction or prosthetic replacement remains unanswered [19], [24]. In our case series a total of five radial head fractures were comminuted (Mason type III), while three were classified as Mason type II and two as Mason type I. All patients with a type III radial head fracture received a cemented bipolar radial head prosthesis. No patient showed signs of loosening of the radial head prosthesis at follow up. All type II radial head fractures were treated with open reduction and internal fixation using mini screws. In all cases of type I fracture the treatment of the radial head dislocation was closed reduction with verification under fluoroscopy. Egol et al. showed that patients with radial head reconstruction or resection surgery achieved similar elbow function [19]. However, Ring et al. found better results in patients who had resections rather than attempted internal fixation [24]. Reynders et al. recommended against early resection of the radial head to improve outcome [27]. Nevertheless, the radial head plays an important role as a secondary stabilizer of the elbow joint in the absence of the medial collateral ligament [25]. Preservation of the length of the radial column by fixation or replacement seems to be a mainstay in the treatment of these injuries [25]. Konrad et al. treated all Mason type II radial head fractures with open reduction and internal fixation, and showed good or excellent results. In the same study Mason type III fractures were treated by radial head resection or reconstruction with poor results. According to the authors, not using prosthetic replacements as a treatment option might have led to these poor results, as the preservation of radiocapitellar contact with a prosthesis or a reconstructed radial head might increase the stability of the ulnohumeral articulation [23]. Furthermore, radial head resection may not be advisable since this may cause a proximal migration of the radius as a result of the frequently associated lesion of the interosseous membrane [6].
Fractures of the coronoid process can lead to instability of the ulnohumeral joint [9], [23], [28]. Therefore, large fractures of the coronoid process should be reduced anatomically to restore the ulnohumeral articulation and minimize the risk of ulnohumeral arthritis [23], [24]. This can be achieved with interfragmentary compression screws inserted through the posterior surface of the ulna either through or adjacent to the plate [24]. According to the Morrey classification there were five type I, three type II, and two type III coronoid fractures in our case series. All coronoid fractures were associated with a Bado type II fracture and were stabilized with lag screws through the ulnar plate or with independent lag screws after indirect repositioning of the fracture. This could further account for the good results and the mild degenerative changes observed. Furthermore, patients received standardized postoperative treatment with early immediate continuous motion, which was not performed in other studies [19], [23], [24], [27].

Conclusion
The Monteggia-like lesions described in this series have rarely been reported before. Our findings demonstrate that good or excellent short-term results can be realized if the injury is classified correctly and a standardized surgical treatment of all components of the injury is achieved. Further studies with larger patient populations and longer follow up periods are needed to evaluate the long-term effectiveness of this treatment concept.